/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/util/TimeoutController.java,v 1.6 2004/04/18 23:51:38 jsdever Exp $
 * $Revision: 480424 $
 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.util;

/**
 * <p>
 * Executes a task with a specified timeout.
 * </p>
 * 
 * @author Ortwin Glueck
 * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
 * @version $Revision: 480424 $
 * @since 2.0
 */
public final class TimeoutController {

	/**
	 * Do not instantiate objects of this class. Methods are static.
	 */
	private TimeoutController() {
	}

	/**
	 * Executes <code>task</code>. Waits for <code>timeout</code> milliseconds
	 * for the task to end and returns. If the task does not return in time, the
	 * thread is interrupted and an Exception is thrown. The caller should
	 * override the Thread.interrupt() method to something that quickly makes
	 * the thread die or use Thread.isInterrupted().
	 * 
	 * @param task
	 *            The thread to execute
	 * @param timeout
	 *            The timeout in milliseconds. 0 means to wait forever.
	 * @throws TimeoutException
	 *             if the timeout passes and the thread does not return.
	 */
	public static void execute(Thread task, long timeout)
			throws TimeoutException {
		task.start();
		try {
			task.join(timeout);
		} catch (InterruptedException e) {
			/* if somebody interrupts us he knows what he is doing */
		}
		if (task.isAlive()) {
			task.interrupt();
			throw new TimeoutException();
		}
	}

	/**
	 * Executes <code>task</code> in a new deamon Thread and waits for the
	 * timeout.
	 * 
	 * @param task
	 *            The task to execute
	 * @param timeout
	 *            The timeout in milliseconds. 0 means to wait forever.
	 * @throws TimeoutException
	 *             if the timeout passes and the thread does not return.
	 */
	public static void execute(Runnable task, long timeout)
			throws TimeoutException {
		Thread t = new Thread(task, "Timeout guard");
		t.setDaemon(true);
		execute(t, timeout);
	}

	/**
	 * Signals that the task timed out.
	 */
	public static class TimeoutException extends Exception {
		/** Create an instance */
		public TimeoutException() {
		}
	}
}
